Purpose: To explore the associations between macular choroidal and retinal thickness and axial elongation in non-myopic and myopic junior students. Methods: In this school-based longitudinal observational study, axial length was measured by optical low-coherence reflectometry, and choroidal thickness and retinal thickness were measured by spectral-domain optical coherence tomography. Myopia was defined as non-cycloplegic objective spherical equivalent refraction ≤ −0.50 diopters. Structural equation modeling and multiple linear regression models were used to analyze the associations between baseline choroidal and retinal thickness with axial elongation. Results: Out of 1307 students examined at baseline in 2017, 1197 (91.58%) returned for follow-up examination in 2018, with a median age of 12.00 years (interquartile range [IQR], 1.00) and included 667 boys (55.72%). Within a 1-year period, the median axial elongation of right eyes was 230 µm (IQR, 180) in boys and 200 µm (IQR, 160) in girls (P = 0.032). The thinner temporal choroidal thickness was associated with greater 1-year axial elongation only in myopic students (β, −0.20; 95% confidence interval [CI], −0.37, −0.03), the thinner temporal retinal thickness was associated with greater 1-year axial elongation in both non-myopic (β, −2.67; 95% CI, −4.52, −0.82) and myopic (β, −0.99; 95% CI, −1.68, −0.30) students, after adjustment for sex, age, and height. Subfoveal and nasal choroidal and retinal thickness were not significantly associated with axial elongation in either non-myopic or myopic students. Conclusions: A thinner temporal choroid at age 12 years may predict greater 1-year axial elongation in myopic students, and a thinner temporal retina may predict greater 1-year axial elongation in both non-myopic and myopic students. This finding may help to identify children at risk and control axial elongation with potential preventive strategies.

Accumulating observational studies suggested that hypercholesterolemia is associated with vascular dementia (VaD); however, the causality between them remains unclear. Hence, the aim of this study is to infer causal associations of circulating lipid-related traits [including high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), apolipoprotein A-I (apoA-I), and apolipoprotein B (apoB)] with VaD jointly using univariable MR (uvMR), multivariable MR (mvMR) and bidirectional two-sample MR methods. Then, the summary-data-based MR (SMR) and two-sample MR analysis were conducted to investigate the association of lipid-lowering drugs target genes expression (including HMGCR, PCSK9, NPC1L1, and APOB) and LDL-C level mediated by these target genes with VaD. The results of forward MR analyses found that genetically predicted HDL-C, LDL-C, TG, apoA-I, and apoB concentrations were not significantly associated with the risk of VaD (all p > 0.05). Notably, there was suggestive evidence for a causal effect of genetically predicted VaD on HDL-C via reverse MR analysis [odds ratio (OR), 0.997; 95% confidence interval (CI), 0.994–0.999; p = 0.022]. On the contrary, the MR results showed no significant relationship between VaD with LDL-C, TG, apoA-I, and apoB. The results for the SMR method found that there was no evidence of association for expression of HMGCR, PCSK9, NPC1L1, and APOB gene with risk of VaD. Furthermore, the result of MR analysis provided evidence for the decreased LDL-C level mediated by gene HMGCR reduced the risk of VaD (OR, 18.381; 95% CI, 2.092–161.474; p = 0.009). Oppositely, none of the IVW methods indicated any causal effects for the other three genes. Using genetic data, this study provides evidence that the VaD risk may cause a reduction of HDL-C level. Additionally, the finding supports the hypothesis that lowering LDL-C levels using statins may be an effective prevention strategy for VaD risk, which requires clinical trials to confirm this result in the future.

The association of specific PM_2.5 chemical constituents with childhood overweight or obesity (OWOB) remain unclear. Furthermore, the long-term impacts of PM_2.5 exposure on the trajectory of children's body mass index (BMI) have not been explored. We conducted a longitudinal study among 1,450,830 Chinese children aged 6-19 years from Beijing and Zhongshan in China during 2005-2018 to examine the associations of PM_2.5 and its chemical constituents with incident OWOB risk. We extracted PM_2.5 mass and five main component exposure from Tracking Air Pollution in China (TAP) dataset. Cox proportional hazards models were applied to quantify exposure-response associations. We further performed principal component analysis (PCA) to handle the multi-collinearity and used quantile g-computation (QGC) approach to analyze the impacts of exposure mixtures. Additionally, we selected 125,863 children with at least 8 physical examination measurements and combined group-based trajectory models (GBTM) with multinomial logistic regression models to explore the impacts of exposure to PM_2.5 mass and five constituents on BMI and BMI Z-score trajectories during 6-19 years. We observed each interquartile range increment in PM_2.5 exposure was significantly associated with a 5.1 % increase in the risk of incident OWOB (95 % confidence Interval [CI]: 1.036-1.066). We also found black carbon, sulfate, organic matter, often linked to fossil combustion, had comparable or larger estimates of the effect (HR = 1.139-1.153) than PM_2.5. Furthermore, Exposure to PM_2.5 mass, sulfate, nitrate, ammonium, organic matter and black carbon was significantly associated with an increased odds of being in a larger BMI trajectory and being assigned to persistent OWOB trajectory. Our findings provide evidence that the constituents mainly from fossil fuel combustion may have a perceptible influence on increased OWOB risk associated with PM_2.5 exposure in China. Moreover, long-term exposure to PM_2.5 contributes to an increased odds of being in a lager BMI and a persistent OWOB trajectories.

Background: Few studies have focused on the prevalence of abdominal obesity in Chinese middle-aged and older adults with a normal body mass index (BMI). Furthermore, it is still unclear whether abdominal obesity is an independent risk factor for type 2 diabetes mellitus (T2DM). Participants with a normal BMI are usually neglected during assessments of abdominal obesity-associated T2DM risk since the current recommendations for medical interventions are mainly focused on overall body mass index rather than fat deposition patterns. Methods: In this study, 7942 normal-BMI participants aged over 45 years from the China Health and Retirement Longitudinal Study were included to assess the prevalence of abdominal obesity defined by waist circumference (WC) or waist-to-height ratio (WHtR). In addition, 4348 normal-BMI individuals with no diabetes at baseline were included to evaluate the association between abdominal obesity and the risk of T2DM with the Cox proportional hazards model. Results: The prevalence (95% confidence interval, CI) of increased WC and substantially increased WC among adults with a normal BMI was 22.0% (21.1%-22.9%) and 18.1% (17.3%-19.0%), respectively. The adjusted hazard ratios and 95% CIs for T2DM incidence were 1.39 (1.05– 1.85) and 1.89 (1.42– 2.53) for those with increased WC and substantially increased WC, respectively, compared to the individuals with a normal WC. Similar HRs were obtained for the association between WHtR and the risk of T2DM. In prediabetic patients, the HRs (95% CIs) for new-onset T2DM for those with increased WC and substantially increased WC were 1.85 (1.27– 2.69) and 2.46 (1.67– 3.61), respectively, when compared with individuals with normal WC. This positive association was observed in women but not in men or adults with normal glucose tolerance (NGT). Conclusion: Abdominal obesity is highly prevalent among middle-aged and older Chinese adults with a normal BMI, and maintaining a normal waist circumference may be beneficial in the prevention of T2DM.